Recirculated air cooling apparatus



June 18, 1968 o. R. PARROTT 3,388,561

RECIRCULATED AIR COOLING APPARATUS Filed Jan. 9. 1967 2 Sheets-Sheet 1 a? FIG-8 78 INVENTOR DELBERT R. PARROTT I'IIS ATTORNEY June 18, 1968 D. R. PARROTT 3,

RECIRCULATED AIR COOLING APPARATUS Filed Jan. 9, 1967 2 Sheets-Sheet z 19 a 4. f k 7 l3 64 63 93 F lG-7 s-2m w". 94 27 United States Patent 3 388,561 RECIRCULATED Alli COOLING APPARATUS Delbert R. Parrott, Englewood, Ohio, assignor to United Aircraft Products, lino, Dayton, Ohio, a corporation of Ohio Filed Jan. 9, 1967, Ser. No. 608,074 10 Claims. (Cl. 62-467) ABSTRACT OF THE DISCLOSURE A unitary assembly of an evaporative liquid storage tank, an evaporator to which liquid from the tank is supplied, a fan-motor combination for recirculating air through the evaporator in heat transfer relation to the liquid, and valve controls, the assembly comprising a unitary package installed in a compartment of cool recirculated compartment air during a variety of heat loads, liquid cool-ant after passing through the evaporator being discharged out of such compartment and the controls featuring means accessible from outside the compartment to vent the tank independently of the evaporator outside the compartment.

This invention relates to recirculated air cooling apparatus, and particularly to systems utilizing an expendable coolant and comprising a self-contained apparatus adapted to be mounted in an electronics compartment or the like to cool such compartment over a predetermined length of time and under conditions of varying heat loads.

The invention is devised to meet specific problems in the cooling art, particularly those relating to avionics cooling.

An object of the invention is to provide a relatively small compact package comprising a self contained apparatus as described.

Another object of the invention is to provide an apparatus making maximum effective use of a supply of stored expendable coolant irrespective of attitude.

A further object of the invention is to provide for the maintaining of a controlled temperature in a recirculated air system despite changes in heat load.

A still further object of the invention is to reduce the hazards of handling and servicing storage tanks containing an expendable coolant by providing means for venting such tanks independently of the normal manner of expediture of such liquid coolant.

Other objects and structural details of the invention will appear from the following description when read in connection with the accompanying drawings, wherein:

FIG. 1 is a view in perspective of self-contained cooling apparatus in accordance with the illustrated embodiment of the invention, a compartment receiving such apparatus being diagrammatically indicated;

FIG. 2 is a top plan view of theapparatus of FIG 1 (the tank being omitted), some parts being broken away for clearness of disclosure;

FIG. 3 is a view in side elevation of the apparatus as shown in FIG. 2;

FIG. 4 is a detail view in longitudinal section of a flow modulating valve controlling access of the coolant to the evaporator;

FIG. 5 is a detailed view of a distributor plate associated with the evaporator, being taken substantially along the line 5-5 of FIG. 4 and at a relatively reduced scale;

FIG. 6 is a detail View fragmentary in form and partly in cross-section, taken substantially along the line 6-6 of FIG. 3; and

FIGS. 7 and 8 are valve details.

Referring to the drawings cooling apparatus in accordance with the instant invention serve-s to cool the air in a compartment containing heat generating means, for

3,388,561 Patented June 18, 1968 ice example a compartment containing avionics. Such a compartment is indicated diagrammatically in FIG. 1 as a broken line box 10. It will be understood that the compartment may assume various shapes and sizes and may include duct work leading to and from a secondary compartment or chamber. The cooling apparatus of the invention is contained within the limited area defined by box 10 and is a fully self-contained unit except to the extent that electrical connections may be required for onoif control and to heat the expendable coolant when this may be required.

The cooling apparatus comprises a tank 11 which is an elongated cylindrical member with closed hemispherical ends. Stored in the tank is an evaporative liquid coolant, for example ammonia. The tank interior is pressurized to a degree to expel liquid ammonia therefrom without reliance upon gravity flow, the cooling system being thus operative irrespective of the attitude assumed in use. The volatile character of the coolant provides adequate pressurization for this purpose within a wide range of temperature values. A tank heater may be provided, operated through a thermal switch, to prevent underpressurization of the system under low ambient temperature conditions.

Other components of the cooling system are arranged alongside the tank 11 generally parallel to the longitudinal axis thereof, the unit comprising a compart package fitting a relatively small compartment 10 and avoiding obstruction to a free flow of the recirculated air.

Other components of the cooling apparatus include a cylindrical housing 12, an evaporator 13 disposed across one end of housing 12, and a heat economizer 14 extending lengthwise over housing 12 and evaporator 13, the housing 12 and tank 11 being disposed about adjacent, parallel longitudinal axes. The structure has a compact form lending itself to simplified installation as described and obviating interference with a free flow of air to and through the evaporator 13.

The housing 12 surrounds and provides a mounting for a fan-motor combination 1546. An adapter 17 attaches one end of housing 12 to what may be considered a rear face of evaporator 13, the adapter 17 being in closing relation to such face. As will hereinafter more clearly appear, air flow passages extend through the evaporator from a front face thereof to the described rear face. Air is drawn through the described passages by rotation of fan 15, is drawn into housing 12 through adapter 17 and is expelled through an opposite or outer end of the housing which may open freely into compartment 10 or be suitably ducted to a connecting compartment. Recirculated air has free access within the compartment 10 to the front face of evaporator 13 for flow through the air flow passages as described. In the operation of the cooling apparatus energizing of motor 16 and rotation of fan 15 are continuous.

The evaporator 13 is a generally conventional plate and fin heat exchanger. 'It is rectangular in shape and provides cross fiow paths for the liquid coolant and for the flowing air. It is comprised of stacked plates 18 (FIG. 4) held spaced apart by marginal inserts 19. These are in alternating transverse relation to one another in a manner to define two sets of flow passes, adjacent ones of which are in alternating or cross flow relationship to one another. Fin material 21 is installed in the flow passes to provide secondary heat transfer surface and to lend strength to the structure. A fragment of an air flow passage appears in FIG. 4. Liquid flow passages are respectively above and below such air flow passage. Thus whereas the air flow passages extend from front to back of the evaporator the liquid flow passages extend from side to side thereof.

The heat economizer 14 is a tube and shell heat exchanger through which the coolant flows through different flow paths respectively before and after passing through evaporator 13. The result is to extract heat from the coolant as it flows from tank 11 to the evaporator, by means hereinafter to be described. The economize-r includes a tubular shell 22 and end closures 23 and 24. Within the shell are longitudinally spaced apart header plates 25 and 26 interconnected by open ended tubes 27. The economizer is held stationary relative to other components of the apparatus by the attachment devices to be described and by a bracket 28 bolted to bosses on top of the evaporator 13.

Near one end, economizer shell 22 is formed with an inlet fitting 29 to which is attached an outwardly projecting housing 31. The latter provides a chamber 32 in open communication with the interior of shell 22 at a location adjacent header plate 26 and between this header plate and the other header plate 25. Inlet tube means 33 connects through. housing 31 into chamber 32 and extends from an outlet fitting 34 on tank 11. Outlet fitting 34 is continuously open so that the coolant under pressure in tank 11 has continuous access through tube 33 and chamber 32 to the interior of shell 22. Within the shell, the coolant flows over and around tubes 27 to an outlet fitting 35. A tube 36 connects fitting 35 to a modulating valve housing 37. interposed in tube 36 is a solenoid controlled on-off valve 38. Valve 38 may be closed to deny coolant flow beyond economizer 14. In the operation of the cooling apparatus, however, valve 38 is open and control of coolant flow is left with valve means in housing 37.

As shown in FIG. 4, the housing 37 has a through longitudinal bore 39 therein. A counterbore 41 from one end of the valve housing defines a seat around bore 39 for a taper nose valve 42 slidable in counterbore 41. A spring 42 based on a screw threaded adjustment nut 43 urges the valve 42 to a seated position closing bore 39. The housing 39 also is counterbored from its opposite end to create from bore 39 a relatively small diameter opening longitudinally disposed in the housing and controlling liquid flow from counterbore 41 into a chamber 44. The latter is in open communication with a through bore 45 in tubular means 46 projecting laterally from housing 37. The counterbore 41 receives coolant directly from tube 36 by way of a housing opening 47. Near its nose portion the valve 42 is reduced in diameter for free access of coolant from inlet opening 47 to the bore 39. The valve 42 further is formed with a radial port 48 and a bore 49 intercommunicating opposite ends of the valve for balancing purposes.

A sealing assembly 51 is installed in the described other end of housing 37 to close chamber 44. A push rod 52 extends to and into closure member 51, with a reduced diameter extension 53 thereof projecting through chamber 42 into contact with the taper nose end of valve 42. The rod 52 is longitudinally adjustable, as Will be seen, so that the position of valve 42 relative to bore 39 becomes a function of the opposing forces represented by rod 52 and spring 42. Under the control of these influences, the valve assumes a variety of positions relative to bore 39, modulating flow therethrough from a closed position to a full flow fully open position.

The rod 52 is surrounded by a compression sprin 54 seated on the relatively stationary closure means 51 and engaged at an opposite end with a collar 55 on rod 52. The push rod extends through and beyond collar 55 and is connected at the end opposite extension 53 to one arm of a bell crank lever 56, another arm of which is engaged by a plunger 57. The lever 56 is pivotally connected to a bracket 58 fastened to the side of housing 12. The plunger 57 is a part of a temperature sensor installed in the side of housing 12. The temperature sensor has a known construction. It is installed in a lateral boss 59 of housing 12 to project in part within the housing and in part outside thereof. The disposition of the sensor is one approximately radial to the axis of housing 12. The inwardly projecting portion of the sensor is so disposed in the path of flow of air drawn through housing 12 by fanmotor combination 1516. Such inwardly projecting portion includes a case 61 containing material which responds to heat by expanding, with the expansion being resolved into an axial extending motion of plunger 57. Extension of plunger 57 rocks lever 56 and moves push rod 52 axially in a direction to unseat valve 42 or to move it leftward against the urging of spring 42. In response to lowering temperatures, the material in case 61 is allowed to contract, the recompressing of such material and the return of push rod 52 being accomplished by spring 54. The latter maintains lever 56 in contact with plunger 57. Accordingly, in response to rising and falling temperatures of the air flowing through housing 12 push rod 52 makes corresponding axially adjusting movements to effect, in conjunction with spring 42, different positions of adjustment of valve 42 relative to bore 39. Coolant flow through the bore to chamber 44 accordingly is affected.

The tubular projection 46 containing flow passage 45 terminates in a vertically elongated flange 62 made fast to the back of a distributor plate 63. The front face of plate 63 is recessed in accordance with a design configuration providing upper and lower horizontal grooves 64 and 65 and an interconnecting vertical groove 66. A longitudinal through bore 67 communicates with groove 66 and is in aligned communicating relation with flow passage 45. The plate 63 is mounted to one side of the evaporator 13 as by being welded or brazed thereto. It is positioned to align horizontal grooves 64 and 65 with liquid flow passages in the evaporator which, as described, are defined by marginal spacer elements 19, such passages having fin strip material 21 contained therein. Accordingly, liquid coolant delivered to chamber 44 in housing 37 is free to flow through passage 45 to distributor plate 63 and is there directed to the grooves 64 and 65 for direct, controlled access to a pair of liquid flow passages in the evaporator. Excessive flow of coolant in liquid form to one evaporator flow passage relative to another is avoided.

In the illustrated instance the liquid flow circuit through the evaporator 13 is of the multiple pass type. It is comprised essentially of two separated flow passes which trace and retrace a pass through the evaporator core. Thus, the two passages communicating with distributor plate grooves 64 and 65 extend across the evaporator to the opposite side thereof and there communicate through a manifold 68 with another pair of flow passes returning toward the first side of the evaporator. There the passes communicate through a manifold 69 with another pair of passes returning to the said other side of the evaporator where they terminate in a manifold 71. A tube 72 connects manifold 71 to the heat economizer 14, commu nicating through end fitting 23 with an end chamber 73 within shell 22 but to the left of and outside the space bounded by header plates 25 and 26. A similar chamber 74 is formed at the opposite end of the economizer. This latter communicates through a passage 75 in a fitting 76 with an exhaust tube 77. As indicated in FIG. 1, tube 77 extends from fitting 76 through compartment 10 and projects to the exterior thereof.

In the operation of the liquid flow circuit, therefore, liquid coolant supplied to the evaporator 13 is conducted in multiple turns through the evaporator core and is then conducted to chamber 73 of the heat economizer. Flowing through tubes 27 the coolant reaches chamber 74 and is vented through fitting 76 and exhaust tube 77 overboard or outside compartment 10. The exhausting coolant does not communicate with the interior of compartment 10.

The coolant leaves tank 11 substantially in liquid form. It reaches the evaporator 13 under a modulating control of valve 42 and passes through the evaporator core in heat transfer relation to ambient air moving through the evaporator under the influence of the fanmotor combination 15-16. The coolant absorbs heat from the air which is drawn from a heat generating source and allows the air to be returned to such source in a cooled condition. Some or all of the liquid coolant changes state so that the condition of the coolant as it discharges from manifold 71 is that of a vapor or a combination of vapor and vaporous liquid. In flowing through the heat economizer 14, the vaporous discharge comes into heat transfer relation through tubes 27 with the liquid coolant enroute to the evaporator and tends to extract heat therefrom. The vaporous fluids finally are discharged from the cooling apparatus as described through exhaust tube 77. The cooled air flows to or is conducted to the heat source, accomplishes its cooling function and returns to the inlet face of evaporator 13. The temperature of the cooled air is sensed by the material in sensor case 61 and appropriate adjustment made as needed in the position of modulating valve 42. A greater or lesser rate of flow of liquid coolant to the evaporator occurs automatically as may be required to maintain the cooled air temperature at or about a selected value.

The system operates, as heretofore noted, over a predetermined length of time. The tank 11 contains coolant in a quantity to provide adequate cooling over that period of time under temperature conditions expected to be encountered. At the conclusion of an operation it may be desirable as a safety measure to vent the tank 11 and thereby avoid possibly unsafe pressure increases therein. The tank should be vented to the exterior of compartment 10. The instant invention has in view vent means operating to the described ends.

The housing 31 through which coolant from tank 11 reaches economizer 14 has a through bore therein providing for longitudinal sliding motion of a valve plunger 78. An outer end of plunger '78 projects outside housing 31 and engages a cam surface 81 on a lever 82. At an intermediate point thereon the lever 82 is pivotally connected to a downward extension of housing 31. At its outer end there is attached to the lever one end of a cable 83. The latter extends through and outside the compartment 1! and terminates in a pull ring 54. With the lever 82 positioned as illustrated the plunger 7 8 engages a low part of cam surface 81. Pulling upon cable 83 rocks lever 82 in a counterclockwise direction as viewed in FIG. 3 causing a high part of cam surface 81 to ride upon plunger 78. The result is to project the plunger inwardly within housing 31. At its inner end plunger 78 projects into chamber 32 and is formed with a valve head 85 adapted to seat on the bottom of such chamber in a manner to close the chamber from communication with a lateral opening 86 in housing 31. A compression spring 87 urges valve head 85 to a seat as described. Spring 87 seats on a member 88 installed in the inner end of housing 31 and having a spider-like configuration in order not to restrict free communication of chamber 32 with the interior of shell 22. The described communication of chamber 32 with outlet opening 86 accordingly normally is denied. Upon inward projection of plunger 78, however, the valve head 85 is unseated and chamber 32 is open to outlet 86. The plunger 78 is reduced in diameter in the vicinity of opening 86 to facilitate flow to such opening. A tube 89 extends between housing 31 and economizer end cap 24 and serves to communicate outlet opening 86 with chamber 74 of the economizer. An opening 91 in end cap 24 connects tube 89 to chamber 74. According to the construction and arrangement of parts, therefore, inward displacement of plunger 78 against the urging of spring 87 opens the interior of tank 11 for venting to the exterior of compartment through chamber 32 of housing 31, outlet opening 86, tube 89 and chamber 74 which as heretofore seen communicates with the compartment exterior through fitting 76 and exhaust tube 77. During venting the released vapors have access also to the interior of economizer 14 and to evaporator 13. However, the area outside compartment 10 will ordinarily be an area of lower pressure. The cable 83 and attached ring 84 serve as a lanyard accessible as described from outside compartment 10 for a selective venting of the tank 11 through the conventional vapor discharge system of the cooling apparatus.

The tube 72 connects to end cap 23 of the heat economizer by way of an intermediate fitting 92 having a telescopic mounting in the cap 23. The cap 92 has a through longitudinal opening 93 therein. A valve 94 is adapted to seat on an interior surface of cap 92 to close passage 93. Valve 94 is disposed at one end of a stem 95 reciprocable in a tubular extension 96 of the header plate 25. A compression spring 97 urges valve 94 to a seated or closed position.

The spring biased valve 94 tends to maintain a predetermined back pressure in the evaporator 13 in a manner to obviate vaporizing of coolant in the evaporator at undesirably low temperatures. It also has a check valve function in denying reverse flow to the evaporator of relatively high pressures vented to the chamber 74. Access of such pressures to the evaporator by way of the shell side of the economizer is denied by valve 38 which is normally closed when lanyard 83-84 is pulled to vent tank 11.

What is claimed is:

1. A self-contained limited area ambient air cooling apparatus using an expendable liquid coolant, including a tank containing an expendable evaporative liquid coolant under pressure, an evaporator providing separated liquid and air flow paths wherein said coolant is brought into heat transfer relation to ambient air, a fan-motor combination arranged to draw ambient air through said evaporator, a housing in enclosing relation to said fanmotor combination open at one end and in closing relation at its other end to a face of said evaporator through which outlet ends of said air flow paths open, inlet ends of said air fiow paths being open to ambient surroundings in said limited area, a temperature sensor installed in said housing to be affected by ambient air after passing through said evaporator, said sensor having means projected in response to increasing air temperature and retractable in response to lowering air temperature, valve actuating means spring urged to a following relation to said last named means, modulated valve means adjusted by said actuating means, said valve means being in a valve housing in a closing relation to inlet ends of liquid flow paths in said evaporator, said valve means being in flow controlling relation to passage means in said valve housing communicating with said inlet ends of said liquid flow paths, a liquid inlet line conducting liquid coolant from said tank to said valve housing, said passage means therein leading under valve control individually to respective inlet ends of said liquid flow paths, the coolant in passing through said liquid flow paths in heat transfer relation to ambient air in said air flow paths being at least in part evaporated and leaving outlet ends of said liquid flow paths at least in part in vapor form, said tank and evaporator and fan-motor housing and valve housing being comprised in a unitary package contained in said limited area, said ambient air being recirculated in said area, means in closing relation to outlet ends of said liquid flow paths in said evaporator, and a discharge line for conducting vapors and vaporous liquid from said last named means out of said limited area.

2. Cooling apparatus according to claim 1, characterized in that said tank is elongated in a longitudinal sense relative to its cross-sectional dimension, said fan-motor housing being arranged along side said tank with its air and liquid passages in cross-flow relationship, said tank and fan-motor housing being disposed in closely adjacent parallel relation with said tank imposing no restriction to a free circulation of air in said limited area through said evaporator to and through said fan-motor housing and then back exteriorly of said cooling apparatus to said evaporator.

3. Cooling apparatus according to claim 1, characterized by a by-pass in said liquid inlet line connecting said inlet line to said discharge line, and a selectively operable vent valve for opening said by-pass, said vent valve normally closing said by-pass.

4. Cooling apparatus according to claim 3, characterized by means for opening said vent valve, said means including a cable extending as a lanyard outside said limited area and there accessible for remote opening of said vent valve.

5. Cooling apparatus according to claim 1, characterized by means accessible from outside said limited area selectively to vent said tank through said discharge line.

6. Cooling apparatus according to claim 1, characterized by a heat exchanger in common communication with said liquid inlet line and said discharge line, said heat exchanger being of the tube and shell kind with said inlet line being connected through the shell side thereof and said discharge line being connected through the tube side, said tube side having an outlet end Communicating with the exterior of said limited area as described.

7. Cooling apparatus according to claim 6, characterized by a controlled by-pass between said liquid inlet line in advance of said heat exchanger and said outlet end of said heat exchanger providing for selective venting of said tank through said discharge line.

8. Cooling apparatus according to claim 1, wherein said temperature sensor is installed in said fan-motor housing to have one end project laterally within the housing and the other end project laterally outside the housing, said projected and retractable means being exposed through said other end, said valve actuating means includ ing a lever contacting said last mentioned means and a push rod engaging said valve means at one end and said lever at its other end, said rod being spring urged to maintain said lever in contact with said projected and retractable means, said one end of said rod being sealingly received in said valve housing to engage said valve means.

9. Cooling apparatus according to claim 1, wherein said passage means in said valve housing includes a passage beyond said valve means terminating in a distributor plate, said plate having a face to engage a face of said evaporator, there being a groove in said plate face in aligned communicating relation with an inlet end of each liquid flow path, said grooves in common communication with said passage.

10. A self contained limited area ambient air cooling apparatus using an expendable liquid coolant, including a tank containing an expendable evaporative liquid coolant under pressure, an evaporator providing separated liquid and air flow paths wherein said coolant is brought into heat transfer relation to ambient air, means to draw ambient air through the evaporator a first liquid flow path from said tank to said evaporator and a second liquid vapor flow path from said evaporator to a location outside said limited area, a heat exchanger in which said flow paths are joined, said heat exchanger providing separated passageways wherein the liquid flowing to said evaporator is brought into heat transfer relation to liquidvapor flowing from said evaporator, said heat exchanger having an inlet for the liquid-vapor flowing from said evaporator, and a valve yieldingly urged to a position closing said inlet, said valve responding to predetermined high pressures in said second flow path in advance of said heat exchanger to open said inlet.

References Cited UNITED STATES PATENTS 2,479,866 '8/ 1949' Rosebaugh -'625l4 X 3,272,258 9/ 1966 Bourquard 625 14 X 3,304,739 2/1967 Erath 62239 X LLOYD L. KING, Primary Examiner. 

